Which term describes a triangle with all sides equal in length and all angles equal?

• A. Straight angle
• B. Approximately
• C. Equilateral triangle
• D. Strategy

Answer: (C)

Equilateral triangle describes a triangle with all sides equal and all angles equal. In such a triangle, every side has the same length, and each interior angle measures 60 degrees. Since the sum of interior angles in any triangle is 180 degrees, three equal angles must each be 60, and equal sides correspond to equal opposite angles. Conversely, if all angles are equal, each is 60 degrees, and the sides opposite those angles must be equal as well, making all three sides equal. The other options aren’t geometric terms for triangles: a straight angle isn’t a triangle, and the words “approximately” and “strategy” don’t describe a triangle’s properties.